<!DOCTYPE html>
<html lang="zh" dir="ltr" class="client-nojs">
<head>
<title>std::span</title>
<meta charset="UTF-8">
<meta name="generator" content="MediaWiki 1.21.2">
<link rel="shortcut icon" href="../../../common/favicon.ico">
<link rel="stylesheet" href="../../../common/ext.css">
<meta name="ResourceLoaderDynamicStyles" content="">
<link rel="stylesheet" href="../../../common/site_modules.css">
<style>a:lang(ar),a:lang(ckb),a:lang(fa),a:lang(kk-arab),a:lang(mzn),a:lang(ps),a:lang(ur){text-decoration:none}#toc{display:none}.editsection{display:none}
/* cache key: mwiki1-mwiki_zh_:resourceloader:filter:minify-css:7:15cea3ec788a65b5187d4018eed543bf */</style>

<script src="../../../common/startup_scripts.js"></script>
<script>if(window.mw){
mw.config.set({"wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"cpp/container/span","wgTitle":"cpp/container/span","wgCurRevisionId":65218,"wgArticleId":10794,"wgIsArticle":true,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":[],"wgBreakFrames":false,"wgPageContentLanguage":"zh","wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"zh","wgMonthNames":["","1月","2月","3月","4月","5月","6月","7月","8月","9月","10月","11月","12月"],"wgMonthNamesShort":["","1月","2月","3月","4月","5月","6月","7月","8月","9月","10月","11月","12月"],"wgRelevantPageName":"cpp/container/span","wgUserVariant":"zh","wgRestrictionEdit":[],"wgRestrictionMove":[]});
}</script><script>if(window.mw){
mw.loader.implement("user.options",function(){mw.user.options.set({"ccmeonemails":0,"cols":80,"date":"default","diffonly":0,"disablemail":0,"disablesuggest":0,"editfont":"default","editondblclick":0,"editsection":0,"editsectiononrightclick":0,"enotifminoredits":0,"enotifrevealaddr":0,"enotifusertalkpages":1,"enotifwatchlistpages":0,"extendwatchlist":0,"externaldiff":0,"externaleditor":0,"fancysig":0,"forceeditsummary":0,"gender":"unknown","hideminor":0,"hidepatrolled":0,"imagesize":2,"justify":0,"math":1,"minordefault":0,"newpageshidepatrolled":0,"nocache":0,"noconvertlink":0,"norollbackdiff":0,"numberheadings":0,"previewonfirst":0,"previewontop":1,"quickbar":5,"rcdays":7,"rclimit":50,"rememberpassword":0,"rows":25,"searchlimit":20,"showhiddencats":0,"showjumplinks":1,"shownumberswatching":1,"showtoc":0,"showtoolbar":1,"skin":"cppreference2","stubthreshold":0,"thumbsize":2,"underline":2,"uselivepreview":0,"usenewrc":0,"watchcreations":0,"watchdefault":0,"watchdeletion":0,
"watchlistdays":3,"watchlisthideanons":0,"watchlisthidebots":0,"watchlisthideliu":0,"watchlisthideminor":0,"watchlisthideown":0,"watchlisthidepatrolled":0,"watchmoves":0,"wllimit":250,"variant":"zh","language":"zh","searchNs0":true,"searchNs1":false,"searchNs2":false,"searchNs3":false,"searchNs4":false,"searchNs5":false,"searchNs6":false,"searchNs7":false,"searchNs8":false,"searchNs9":false,"searchNs10":false,"searchNs11":false,"searchNs12":false,"searchNs13":false,"searchNs14":false,"searchNs15":false,"gadget-MathJax":1,"gadget-ColiruCompiler":1});;},{},{});mw.loader.implement("user.tokens",function(){mw.user.tokens.set({"editToken":"+\\","patrolToken":false,"watchToken":false});;},{},{});
/* cache key: mwiki1-mwiki_zh_:resourceloader:filter:minify-js:7:258d7cd6aa9aa67dee25e01fb6a9e505 */
}</script>
<script>if(window.mw){
mw.loader.load(["mediawiki.page.startup","mediawiki.legacy.wikibits","mediawiki.legacy.ajax"]);
}</script>
<style type="text/css">/*<![CDATA[*/
.source-cpp {line-height: normal;}
.source-cpp li, .source-cpp pre {
	line-height: normal; border: 0px none white;
}
/**
 * GeSHi Dynamically Generated Stylesheet
 * --------------------------------------
 * Dynamically generated stylesheet for cpp
 * CSS class: source-cpp, CSS id: 
 * GeSHi (C) 2004 - 2007 Nigel McNie, 2007 - 2008 Benny Baumann
 * (http://qbnz.com/highlighter/ and http://geshi.org/)
 * --------------------------------------
 */
.cpp.source-cpp .de1, .cpp.source-cpp .de2 {font: normal normal 1em/1.2em monospace; margin:0; padding:0; background:none; vertical-align:top;}
.cpp.source-cpp  {font-family:monospace;}
.cpp.source-cpp .imp {font-weight: bold; color: red;}
.cpp.source-cpp li, .cpp.source-cpp .li1 {font-weight: normal; vertical-align:top;}
.cpp.source-cpp .ln {width:1px;text-align:right;margin:0;padding:0 2px;vertical-align:top;}
.cpp.source-cpp .li2 {font-weight: bold; vertical-align:top;}
.cpp.source-cpp .kw1 {color: #0000dd;}
.cpp.source-cpp .kw2 {color: #0000ff;}
.cpp.source-cpp .kw3 {color: #0000dd;}
.cpp.source-cpp .kw4 {color: #0000ff;}
.cpp.source-cpp .co1 {color: #909090;}
.cpp.source-cpp .co2 {color: #339900;}
.cpp.source-cpp .coMULTI {color: #ff0000; font-style: italic;}
.cpp.source-cpp .es0 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es1 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es2 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es3 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es4 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es5 {color: #008000; font-weight: bold;}
.cpp.source-cpp .br0 {color: #008000;}
.cpp.source-cpp .sy0 {color: #008000;}
.cpp.source-cpp .sy1 {color: #000080;}
.cpp.source-cpp .sy2 {color: #000040;}
.cpp.source-cpp .sy3 {color: #000040;}
.cpp.source-cpp .sy4 {color: #008080;}
.cpp.source-cpp .st0 {color: #008000;}
.cpp.source-cpp .nu0 {color: #000080;}
.cpp.source-cpp .nu6 {color: #000080;}
.cpp.source-cpp .nu8 {color: #000080;}
.cpp.source-cpp .nu12 {color: #000080;}
.cpp.source-cpp .nu16 {color:#000080;}
.cpp.source-cpp .nu17 {color:#000080;}
.cpp.source-cpp .nu18 {color:#000080;}
.cpp.source-cpp .nu19 {color:#000080;}
.cpp.source-cpp .ln-xtra, .cpp.source-cpp li.ln-xtra, .cpp.source-cpp div.ln-xtra {background-color: #ffc;}
.cpp.source-cpp span.xtra { display:block; }

/*]]>*/
</style><!--[if lt IE 7]><style type="text/css">body{behavior:url("/mwiki/skins/cppreference2/csshover.min.htc")}</style><![endif]--></head>
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_container_span skin-cppreference2 action-view cpp-navbar">
        <!-- header -->
        <!-- /header -->
        <!-- content -->
<div id="cpp-content-base">
            <div id="content">
                <a id="top"></a>
                <div id="mw-js-message" style="display:none;"></div>
                                <!-- firstHeading -->
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>span</h1>
                <!-- /firstHeading -->
                <!-- bodyContent -->
                <div id="bodyContent">
                                        <!-- tagline -->
                    <div id="siteSub">来自cppreference.com</div>
                    <!-- /tagline -->
                                        <!-- subtitle -->
                    <div id="contentSub"><span class="subpages">&lt; <a href="../../cpp.html" title="cpp">cpp</a>‎ | <a href="https://zh.cppreference.com/w/cpp/container" title="cpp/container">container</a></span></div>
                    <!-- /subtitle -->
                                                            <!-- bodycontent -->
                    <div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr"><div class="t-navbar" style=""><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="../../cpp.html" title="cpp"> C++</a><div class="t-navbar-menu"><div><div><table class="t-nv-begin" cellpadding="0" style="line-height:1.1em;">
<tr class="t-nv"><td colspan="5"> <a href="../language.html" title="cpp/language">语言</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../header.html" title="cpp/header">标准库头文件</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../freestanding.html" title="cpp/freestanding"> 自立与有宿主实现</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../named_req.html" title="cpp/named req">具名要求</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../utility.html#.E8.AF.AD.E8.A8.80.E6.94.AF.E6.8C.81" title="cpp/utility">语言支持库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../concepts.html" title="cpp/concepts">概念库</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../error.html" title="cpp/error">诊断库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../utility.html" title="cpp/utility">工具库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../string.html" title="cpp/string">字符串库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="https://zh.cppreference.com/w/cpp/container" title="cpp/container">容器库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../iterator.html" title="cpp/iterator">迭代器库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../ranges.html" title="cpp/ranges"> 范围库</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../algorithm.html" title="cpp/algorithm">算法库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../numeric.html" title="cpp/numeric">数值库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../io.html" title="cpp/io">输入/输出库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../locale.html" title="cpp/locale">本地化库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../regex.html" title="cpp/regex">正则表达式库</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../atomic.html" title="cpp/atomic">原子操作库</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../thread.html" title="cpp/thread">线程支持库</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../filesystem.html" title="cpp/filesystem">文件系统库</a> <span class="t-mark-rev t-since-cxx17">(C++17)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../experimental.html" title="cpp/experimental">技术规范</a> </td></tr>
</table></div><div></div></div></div></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="https://zh.cppreference.com/w/cpp/container" title="cpp/container">容器库</a><div class="t-navbar-menu"><div><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="array.html" title="cpp/container/array"><span class="t-lines"><span>array</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="vector.html" title="cpp/container/vector"><span class="t-lines"><span>vector</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="deque.html" title="cpp/container/deque"><span class="t-lines"><span>deque</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="forward_list.html" title="cpp/container/forward list"><span class="t-lines"><span>forward_list</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="list.html" title="cpp/container/list"><span class="t-lines"><span>list</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="set.html" title="cpp/container/set"><span class="t-lines"><span>set</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="multiset.html" title="cpp/container/multiset"><span class="t-lines"><span>multiset</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="map.html" title="cpp/container/map"><span class="t-lines"><span>map</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="multimap.html" title="cpp/container/multimap"><span class="t-lines"><span>multimap</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="unordered_set.html" title="cpp/container/unordered set"><span class="t-lines"><span>unordered_set</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="unordered_multiset.html" title="cpp/container/unordered multiset"><span class="t-lines"><span>unordered_multiset</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="unordered_map.html" title="cpp/container/unordered map"><span class="t-lines"><span>unordered_map</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="unordered_multimap.html" title="cpp/container/unordered multimap"><span class="t-lines"><span>unordered_multimap</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="stack.html" title="cpp/container/stack"><span class="t-lines"><span>stack</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="queue.html" title="cpp/container/queue"><span class="t-lines"><span>queue</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="priority_queue.html" title="cpp/container/priority queue"><span class="t-lines"><span>priority_queue</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><strong class="selflink"><span class="t-lines"><span>span</span></span></strong></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div></td></tr>
</table></div><div></div></div></div></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><strong class="selflink"><tt>std::span</tt></strong><div class="t-navbar-menu"><div><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-h1"><td colspan="5">成员函数</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/span.html" title="cpp/container/span/span"><span class="t-lines"><span>span::span</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/operator%3D.html" title="cpp/container/span/operator="><span class="t-lines"><span>span::operator=</span></span></a></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5">元素访问</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/front.html" title="cpp/container/span/front"><span class="t-lines"><span>span::front</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/back.html" title="cpp/container/span/back"><span class="t-lines"><span>span::back</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/operator_at.html" title="cpp/container/span/operator at"><span class="t-lines"><span>span::operator[]</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/data.html" title="cpp/container/span/data"><span class="t-lines"><span>span::data</span></span></a></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5">迭代器</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/begin.html" title="cpp/container/span/begin"><span class="t-lines"><span>span::begin</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/end.html" title="cpp/container/span/end"><span class="t-lines"><span>span::end</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/rbegin.html" title="cpp/container/span/rbegin"><span class="t-lines"><span>span::rbegin</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/rend.html" title="cpp/container/span/rend"><span class="t-lines"><span>span::rend</span></span></a></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5">观察器</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/empty.html" title="cpp/container/span/empty"><span class="t-lines"><span>span::empty</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/size.html" title="cpp/container/span/size"><span class="t-lines"><span>span::size</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/size_bytes.html" title="cpp/container/span/size bytes"><span class="t-lines"><span>span::size_bytes</span></span></a></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5">子视图</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/first.html" title="cpp/container/span/first"><span class="t-lines"><span>span::first</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/last.html" title="cpp/container/span/last"><span class="t-lines"><span>span::last</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/subspan.html" title="cpp/container/span/subspan"><span class="t-lines"><span>span::subspan</span></span></a></div></div></td></tr>
<tr class="t-nv-h1"><td colspan="5">非成员函数</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/as_bytes.html" title="cpp/container/span/as bytes"><span class="t-lines"><span>as_bytes</span><span>as_writable_bytes</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/get.html" title="cpp/container/span/get"><span class="t-lines"><span>get</span></span></a></div></div></td></tr>
<tr class="t-nv-h1"><td colspan="5">非成员常量</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="span/dynamic_extent.html" title="cpp/container/span/dynamic extent"><span class="t-lines"><span>dynamic_extent</span></span></a></div></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> <a href="span/deduction_guides.html" title="cpp/container/span/deduction guides">推导指引</a></td></tr>
</table></div><div></div></div></div></div><div class="t-navbar-sep"> </div></div>
<table class="t-dcl-begin"><tbody>
<tr class="t-dsc-header">
<td> <div>定义于头文件 <code><a href="../header/span.html" title="cpp/header/span">&lt;span&gt;</a></code>
 </div></td>
<td></td>
<td></td>
</tr>
<tr class="t-dcl t-since-cxx20">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <br>
<p>    <span class="kw1">class</span> T, <br>
    <a href="../types/size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> Extent <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">dynamic_extent</span><br>
</p>
<span class="sy1">&gt;</span> <span class="kw1">class</span> span<span class="sy4">;</span></span></div></td>
<td class="t-dcl-nopad">  </td>
<td> <span class="t-mark-rev t-since-cxx20">(C++20 起)</span> </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
</tbody></table>
<p>类模板 <code>span</code> 所描述的对象能指代对象的相接序列，序列的首元素在零位置。 <code>span</code> 能拥有<i>静态</i>长度，该情况下序列中的元素数已知并编码于类型中，或拥有<i>动态</i>长度。
</p><p>典型实现只保有二个成员：指向 <code>T</code> 的指针和大小。
</p>
<h3><span class="mw-headline" id=".E6.A8.A1.E6.9D.BF.E5.BD.A2.E5.8F.82">模板形参</span></h3>
<table class="t-par-begin">


<tr class="t-par">
<td>  T
</td>
<td> -
</td>
<td> 元素类型；必须是完整类型且非抽象类
</td></tr>
<tr class="t-par">
<td>  Extent
</td>
<td> -
</td>
<td> 序列中的元素数，或若它为动态则为 <code>std::dynamic_extent</code>
</td></tr></table>
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
<table class="t-dsc-begin">

<tr class="t-dsc-sep">
<td colspan="2">  
</td></tr>
<tr class="t-dsc-hitem">
<td> 成员类型
</td>
<td> 定义
</td></tr>


<tr class="t-dsc">
<td>  <code>element_type</code>
</td>
<td>  <code>T</code>
</td></tr>

<tr class="t-dsc">
<td>  <code>value_type</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="../types/remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span></span></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>size_type</code>
</td>
<td>  <span class="t-lc"><a href="../types/size_t.html" title="cpp/types/size t">std::size_t</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>difference_type</code>
</td>
<td>  <span class="t-lc"><a href="../types/ptrdiff_t.html" title="cpp/types/ptrdiff t">std::ptrdiff_t</a></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>pointer</code>
</td>
<td>  <code>T*</code>
</td></tr>

<tr class="t-dsc">
<td>  <code>const_pointer</code>
</td>
<td>  <code>const T*</code>
</td></tr>

<tr class="t-dsc">
<td>  <code>reference</code>
</td>
<td>  <code>T&amp;</code>
</td></tr>

<tr class="t-dsc">
<td>  <code>const_reference</code>
</td>
<td>  <code>const T&amp;</code>
</td></tr>

<tr class="t-dsc">
<td>  <code>iterator</code>
</td>
<td> 实现定义的<a href="../named_req/RandomAccessIterator.html" title="cpp/named req/RandomAccessIterator"><i>遗留随机访问迭代器</i> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyRandomAccessIterator)</span> </a>、<a href="../named_req/ConstexprIterator.html" title="cpp/named req/ConstexprIterator"><i>常量表达式迭代器</i> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(ConstexprIterator)</span> </a>兼<a href="../named_req/ContiguousIterator.html" title="cpp/named req/ContiguousIterator"><i>遗留连续迭代器</i> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyContiguousIterator)</span> </a>，其 <code>value_type</code> 为 <code>value_type</code>
</td></tr>

<tr class="t-dsc">
<td>  <code>reverse_iterator</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="../iterator/reverse_iterator.html"><span class="kw658">std::<span class="me2">reverse_iterator</span></span></a><span class="sy1">&lt;</span>iterator<span class="sy1">&gt;</span></span></span>
</td></tr>

<tr class="t-dsc">
<td>  <code>const_reverse_iterator</code>
</td>
<td>  <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="../iterator/reverse_iterator.html"><span class="kw658">std::<span class="me2">reverse_iterator</span></span></a><span class="sy1">&lt;</span>const_iterator<span class="sy1">&gt;</span></span></span>
</td></tr>
</table>
<p>注意：若 <code>T</code> 无 const 限定则 <code>iterator</code> 为可变迭代器。
</p><p><a href="../named_req/Container.html" title="cpp/named req/Container"><i>容器</i> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Container)</span> </a>的迭代器类型上的所有要求亦应用于 <code>span</code> 的 <code>iterator</code> 类型。
</p>
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">成员常量</span></h3>
<table class="t-dcl-begin"><tbody>

<tr class="t-dcl">
<td class="t-dcl-nopad"> <div><span class="mw-geshi cpp source-cpp"><span class="kw4">static</span> <span class="kw4">constexpr</span> <a href="../types/size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> extent <span class="sy1">=</span> Extent<span class="sy4">;</span></span></div></td>
<td class="t-dcl-nopad">  </td>
<td class="t-dcl-nopad">  </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
</tbody></table>
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
<table class="t-dsc-begin">

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div t-dsc-member-nobold-div"><div><a href="span/span.html" title="cpp/container/span/span"> <span class="t-lines"><span>(构造函数)</span></span></a></div></div>
</td>
<td>  构造 <code>span</code> <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/operator%3D.html" title="cpp/container/span/operator="> <span class="t-lines"><span>operator=</span></span></a></div></div>
</td>
<td>  赋值 <code>span</code> <br> <span class="t-mark">(公开成员函数)</span> </td></tr>


<tr>
<td colspan="2"> <h5> <span class="mw-headline" id=".E8.BF.AD.E4.BB.A3.E5.99.A8"> 迭代器 </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/begin.html" title="cpp/container/span/begin"> <span class="t-lines"><span>begin</span></span></a></div></div>
</td>
<td>  返回指向序列起始的迭代器 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/end.html" title="cpp/container/span/end"> <span class="t-lines"><span>end</span></span></a></div></div>
</td>
<td>  返回指向序列末尾的迭代器 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/rbegin.html" title="cpp/container/span/rbegin"> <span class="t-lines"><span>rbegin</span></span></a></div></div>
</td>
<td>  返回指向序列逆向起始的逆向迭代器 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/rend.html" title="cpp/container/span/rend"> <span class="t-lines"><span>rend</span></span></a></div></div>
</td>
<td>  返回指向序列逆向末尾的逆向迭代器 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>


<tr>
<td colspan="2"> <h5> <span class="mw-headline" id=".E5.85.83.E7.B4.A0.E8.AE.BF.E9.97.AE"> 元素访问 </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/front.html" title="cpp/container/span/front"> <span class="t-lines"><span>front</span></span></a></div></div>
</td>
<td>  访问第一个元素 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/back.html" title="cpp/container/span/back"> <span class="t-lines"><span>back</span></span></a></div></div>
</td>
<td>   访问最后一个元素  <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/operator_at.html" title="cpp/container/span/operator at"> <span class="t-lines"><span>operator[]</span></span></a></div></div>
</td>
<td>  访问序列的元素 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/data.html" title="cpp/container/span/data"> <span class="t-lines"><span>data</span></span></a></div></div>
</td>
<td>  返回指向元素序列起始的指针 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>


<tr>
<td colspan="2"> <h5> <span class="mw-headline" id=".E8.A7.82.E5.AF.9F.E5.99.A8"> 观察器 </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/size.html" title="cpp/container/span/size"> <span class="t-lines"><span>size</span></span></a></div></div>
</td>
<td>  返回序列中的元素数 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/size_bytes.html" title="cpp/container/span/size bytes"> <span class="t-lines"><span>size_bytes</span></span></a></div></div>
</td>
<td>  返回以字节表示的序列大小 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/empty.html" title="cpp/container/span/empty"> <span class="t-lines"><span>empty</span></span></a></div></div>
</td>
<td>  检查序列是否为空 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>


<tr>
<td colspan="2"> <h5> <span class="mw-headline" id=".E5.AD.90.E8.A7.86.E5.9B.BE"> 子视图 </span></h5>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/first.html" title="cpp/container/span/first"> <span class="t-lines"><span>first</span></span></a></div></div>
</td>
<td>  获得由序列首 N 个元素组成的子段 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/last.html" title="cpp/container/span/last"> <span class="t-lines"><span>last</span></span></a></div></div>
</td>
<td>  获得由序列末 N 个元素组成的子段 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/subspan.html" title="cpp/container/span/subspan"> <span class="t-lines"><span>subspan</span></span></a></div></div>
</td>
<td>  获得子段 <br> <span class="t-mark">(公开成员函数)</span> </td></tr>
</table>
<h3><span class="mw-headline" id=".E9.9D.9E.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">非成员函数</span></h3>
<table class="t-dsc-begin">

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/as_bytes.html" title="cpp/container/span/as bytes"> <span class="t-lines"><span>as_bytes</span><span>as_writable_bytes</span></span></a></div></div>
</td>
<td>  转换 <code>span</code> 为对其底层字节的视图 <br> <span class="t-mark">(函数模板)</span> </td></tr>
</table>
<h3><span class="mw-headline" id=".E9.9D.9E.E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">非成员常量</span></h3>
<table class="t-dsc-begin">

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="span/dynamic_extent.html" title="cpp/container/span/dynamic extent"> <span class="t-lines"><span>dynamic_extent</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   <code>size_t</code> 类型常量，指明 <code>span</code> 拥有动态长度 <br> <span class="t-mark">(常量)</span> </td></tr>
</table>
<h3><span class="mw-headline" id=".E8.BE.85.E5.8A.A9.E6.A8.A1.E6.9D.BF">辅助模板</span></h3>
<table class="t-dcl-begin"><tbody>

<tr class="t-dcl">
<td class="t-dcl-nopad"> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> T, <a href="../types/size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> Extent<span class="sy1">&gt;</span><br>
<span class="kw1">inline</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> ranges<span class="sy4">::</span><span class="me2">enable_borrowed_range</span><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">span</span><span class="sy1">&lt;</span>T, Extent<span class="sy1">&gt;&gt;</span> <span class="sy1">=</span> <span class="kw2">true</span><span class="sy4">;</span></span></div></td>
<td class="t-dcl-nopad">  </td>
<td class="t-dcl-nopad">  </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
</tbody></table>
<p><a href="../ranges/borrowed_range.html" title="cpp/ranges/borrowed range"><tt>std::ranges::enable_borrowed_range</tt></a> 的此特化使得 <code>span</code> 满足 <a href="../ranges/borrowed_range.html" title="cpp/ranges/borrowed range"><tt>borrowed_range</tt></a> 。
</p>
<table class="t-dcl-begin"><tbody>

<tr class="t-dcl">
<td class="t-dcl-nopad"> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> T, <a href="../types/size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> Extent<span class="sy1">&gt;</span><br>
<p><span class="kw1">inline</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> ranges<span class="sy4">::</span><span class="me2">enable_view</span><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">span</span><span class="sy1">&lt;</span>T, Extent<span class="sy1">&gt;&gt;</span> <span class="sy1">=</span> <br>
</p>
    Extent <span class="sy1">==</span> <span class="nu0">0</span> <span class="sy3">||</span> Extent <span class="sy1">==</span> dynamic_extent<span class="sy4">;</span></span></div></td>
<td class="t-dcl-nopad">  </td>
<td class="t-dcl-nopad">  </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
</tbody></table>
<p><a href="../ranges/view.html" title="cpp/ranges/view"><tt>std::ranges::enable_view</tt></a> 的此特化使零或动态长度的 <code>span</code> 满足 <a href="../ranges/view.html" title="cpp/ranges/view"><tt>view</tt></a> 。非零静态长度的 span 非 <a href="../concepts/default_initializable.html" title="cpp/concepts/default initializable"><tt>default_initializable</tt></a> 从而不是视图。
</p>
<h3><span class="mw-headline" id=".E6.8E.A8.E5.AF.BC.E6.8C.87.E5.BC.95"><a href="span/deduction_guides.html" title="cpp/container/span/deduction guides">推导指引</a></span></h3>

<!-- 
NewPP limit report
Preprocessor visited node count: 8304/1000000
Preprocessor generated node count: 12752/1000000
Post‐expand include size: 161789/2097152 bytes
Template argument size: 30853/2097152 bytes
Highest expansion depth: 20/40
Expensive parser function count: 0/100
-->

<!-- Saved in parser cache with key mwiki1-mwiki_zh_:pcache:idhash:10794-0!*!0!!zh!*!zh!* and timestamp 20200305180250 -->
</div>                    <!-- /bodycontent -->
                                        <!-- printfooter -->
                    <div class="printfooter">
                    来自“<a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/container/span&amp;oldid=65218">https://zh.cppreference.com/mwiki/index.php?title=cpp/container/span&amp;oldid=65218</a>”                    </div>
                    <!-- /printfooter -->
                                                            <!-- catlinks -->
                    <!-- /catlinks -->
                                                            <div class="visualClear"></div>
                    <!-- debughtml -->
                                        <!-- /debughtml -->
                </div>
                <!-- /bodyContent -->
            </div>
        </div>
        <!-- /content -->
        <!-- footer -->
        <div id="cpp-footer-base" class="noprint">
            <div id="footer">
                        <div id="cpp-navigation">
            <h5>导航</h5>
            <ul><li><a href="https://zh.cppreference.com/w/cpp/container/span">Online version</a></li><li>Offline version retrieved 2020-03-14 18:00.</li></ul></div>
                        <ul id="footer-info">
                                    <li id="footer-info-lastmod"> 本页面最后修改于2020年3月5日 (星期四) 10:02。</li>
                                    <li id="footer-info-viewcount">此页面已被浏览过14,024次。</li>
                            </ul>
                    </div>
        </div>
        <!-- /footer -->
        <script>if(window.mw){
mw.loader.state({"site":"loading","user":"missing","user.groups":"ready"});
}</script>
<script src="../../../common/skin_scripts.js"></script>
<script>if(window.mw){
mw.loader.load(["mediawiki.action.view.postEdit","mediawiki.user","mediawiki.page.ready","mediawiki.searchSuggest","mediawiki.hidpi","ext.gadget.MathJax","ext.gadget.ColiruCompiler"], null, true);
}</script>
<script src="../../../common/site_scripts.js"></script>
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-2828341-1']);
_gaq.push(['_setDomainName', 'cppreference.com']);
_gaq.push(['_trackPageview']);
</script><!-- Served in 0.069 secs. -->
	</body>
<!-- Cached 20200305182024 -->
</html>